A vacuum system may assist an operator or another system to actuate various vehicle systems. For example, a vacuum system may be used to assist a driver applying vehicle brakes, regulating turbocharger operation, fuel vapor purging, heating and ventilation system actuation, and driveline component actuation. However, it is possible for a vacuum system to develop a vacuum leak so that performance of the vacuum system may degrade. Further, vacuum systems can include components that may make it difficult to diagnose vacuum system leakage because the components provide some isolation within portions of the vacuum system. For example, vacuum regulators in a vacuum system may make it more difficult to determine vacuum leaks between vacuum lines upstream and downstream of the vacuum regulators.
The inventors herein have recognized the above-mentioned disadvantages and have developed a method for diagnosing a vacuum system, comprising: commanding an electric vacuum regulator supplying vacuum to a turbocharger wastegate to a vacuum level during a period of vacuum consumption less than a threshold level; and diagnosing a condition of vacuum system degradation in response to a vacuum level in a pneumatic passage extending between the electric vacuum regulator and the turbocharger wastegate.
By adjusting a duty cycle applied to an electric vacuum regulator, it may be possible to diagnose vacuum system leaks upstream and downstream of a vacuum regulator with a single sensor. In one example, a sensor used to control vacuum within a wastegate reservoir may be a basis for determining vacuum system degradation and vacuum leaks within a vacuum system. Thus, the sensor may provide more than one function so that system cost may be reduced as compared to systems that my employ multiple sensors for multiple purposes.
The present description may provide several advantages. For example, the approach may reduce cost of a vacuum system that includes diagnostics. Further, the approach can reduce system complexity since during some conditions vacuum within the system may be controlled to a single level rather than monitoring different levels of vacuum.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.